Power transformers are used in the transmission of energy from a point of energy generation to a point of energy use. The generated energy is often transmitted over long distances at high voltages to a substation where a transformer reduces the voltage level of the transmitted power for consumer consumption.
The power transformer includes primary windings, which receive varying currents and voltages to generate varying magnetic flux in a transformer core. The varying magnetic flux induces voltage in secondary windings, which provides output voltages and currents. The values of the output voltages and currents are directly related to the input voltages and currents as a result of the ratio of the number of turns of primary windings to the number of turns of secondary windings.
While the construction of a power transformer can appear to be relatively straightforward, medium and large power transformers suffer from certain disadvantages. For instance, such power transformers have a high non-recurring engineering effort. Very few “mass-produced” units (multiple units of the same size, shape, and electrical characteristics) are generally possible due to site-specific voltage, impedance, and cost requirements. On average, only 1.3 transformer units are built for each particular application, consequently multiple transformer units of the same type not needed. Power transformers also require a relatively high production lead time. Typically, more than five months are required from an initial customer request to a final delivery of the transformer.
Power transformers are also difficult to transport. A single transformer can weigh one-hundred (100) tons, or more, and cannot be easily transported over existing roads. Due to these difficulties, special transportation arrangements are required to select an adequate roadway and to select a time of delivery, often during the middle of the night to reduce the ill effects on traffic flow. When a transformer fails, the failure is experienced as a single point of failure. If something goes wrong with the power transformer, the entire transformer unit goes offline, which affects the entire system to which it provides energy. These failures are especially problematic at certain power substations that are deemed “critical.” What is needed, therefore, is a power transformer that overcomes these deficiencies.